Normal Vibrations and Urey-Bradley Force Constants of Methyl Amine

Using least-squares fitting to the experimental frequencies, the Urey-Bradley force constants and their uncertainties have been calculated for methyl amine and deuterated derivatives. From the calculation, new assignments of the NH2 twisting vibrations are proposed: CH3NH2, 977 cm-1; CH3ND2, 744 cm-1; CD3NH2, 1078 cm-1; and CD3ND2, 701 cm-1. Potential-energy distributions of these four molecules are reported.